There is going something strange with few buttons on my device. From one second to another my escape-, zero- and trackball-ok-button do not work correctly.
When I press escape it gives me 'hl', zero=yi, ok=uo

I restarted it, pulled the battery, even wiped it and put my last backup on it and still have the failures.

Yep, sounds just like what happened with mine when I got a little too aggressive cleaning the trackball with windex. Thankfully a little time allowed it all to dry out and get back to normal. And I finally figured out how to properly clean my trackball (though I'll probably just replace it nexts time it gets gnarly).